In a mobile communication network, in particular in a Mobile LTE Relay communication network, the air-interface of the network—which is the E-UTRAN part (evolved UMTS Terrestrial Radio Access network) of the LTE network—comprises networks nodes, called eNBs, E-UTRAN NodeBs, operating each a fixed radio cell for serving user equipments, UE, located within the coverage area of the respective radio cell.
For the reasons of coverage extension, the E-UTRAN supports a relaying by mobile relay nodes wirelessly connected to an eNB serving the mobile relay node, the eNB therefore is called Donor eNB, DeNB, via a modified version of the E-UTRAN radio interface which is called Un interface.
For the user equipments served by the mobile radio cell operated by the mobile relay node, the mobile relay node appears as a mobile base station. Therefore the user equipments need to know the physical cell ID assigned to the mobile radio cell operated by the mobile relay node for sending and receiving communication via the mobile relay node over the mobile communication network.